Comparative Evaluation of Three Chitin Synthesis Inhibitor Termite Baits Using Multiple Bioassay Designs

Use of chitin synthesis inhibitors has revolutionized the potential impact of termite baiting systems. Several chitin synthesis inhibitors have been used or tested against subterranean termites. We evaluated the effect of lufenuron on bait matrix consumption and mortality of Coptotermes formosanus and compared it with 2 other chitin synthesis inhibitors presently used for termite control: diflubenzuron and noviflumuron. Laboratory no-choice and multi-chamber bioassay designs were employed. At the end of 6 weeks, in both the no-choice and multi-chamber tests, mortality was significantly higher in all the chitin synthesis inhibitor treatments as compared to the controls; however, lufenuron treatment had significantly higher mortality than the other chitin synthesis inhibitors. Multi-chamber tests suggested no sign of feeding deterrence with any of the chitin synthesis inhibitors at the concentrations tested. Consumption of lufenuron cardboard or noviflumuron bait matrix was similar to that of control cardboard in the no-choice tests. We conclude that, based on the overall bait consumption and mortality data, lufenuron was at least as effective as noviflumuron and diflubenzuron

Comparative Evaluation of Three Chitin Synthesis Inhibitor Termite Baits Using Multiple Bioassay Designs

Use of chitin synthesis inhibitors has revolutionized the potential impact of termite baiting systems. Several chitin synthesis inhibitors have been used or tested against subterranean termites. We evaluated the effect of lufenuron on bait matrix consumption and mortality of Coptotermes formosanus and compared it with 2 other chitin synthesis inhibitors presently used for termite control: diflubenzuron and noviflumuron. Laboratory no-choice and multi-chamber bioassay designs were employed. At the end of 6 weeks, in both the no-choice and multi-chamber tests, mortality was significantly higher in all the chitin synthesis inhibitor treatments as compared to the controls; however, lufenuron treatment had significantly higher mortality than the other chitin synthesis inhibitors. Multi-chamber tests suggested no sign of feeding deterrence with any of the chitin synthesis inhibitors at the concentrations tested. Consumption of lufenuron cardboard or noviflumuron bait matrix was similar to that of control cardboard in the no-choice tests. We conclude that, based on the overall bait consumption and mortality data, lufenuron was at least as effective as noviflumuron and diflubenzuron

Novel free ceramides as components of the soldier defense gland of the Formosan subterranean termite (Coptotermes formosanus)

Of the lipid extracts of the defense secretion from the Formosan subterranean termite, Coptotermes formosanus Shiraki, on high-performance thin-layer chromatography analysis, no glycolipids or phospholipids were detected, but free fatty acids and three novel ceramides were found (termed TL-1, TL-2, and TL-3). Free fatty acids were confirmed to be lignoceric acid (C24:0) and hexacosanoic acid (C26:0), as described previously [Chen, J., G. Henderson, and R. A. Laine. 1999. Lignoceric acid and hexacosanoic acid: major components of soldier frontal gland secretions of the Formosan subterranean termite (Coptotermes formosanus). J. Chem. Ecol. 25: 817-824]. TL-1, TL-2, and TL-3 were characterized as ceramides differing in hydrophobicity based on results of matrix-assisted laser desorption-ionization time-of-flight mass spectrometry analysis, mild alkaline treatment, GC-MS analysis of fatty acid methylesters, and GC-MS analysis of sphingoid long-chain bases (LCBs) as trimethylsilyl derivatives. Fatty acids in TL-1 and TL-2 were C18:0, C20:0, and C22:0, and those in TL-3 were 2-hydroxy C18:0, C20:0, and C22:0. The most predominant LCB in TL-2 was a novel trihydroxy C14-sphingosine, 1,3,9-trihydroxy-2-amino-6-tetradecene. TL-3 contained C18-sphinganine and two kinds of novel sphingadienines, 1,3-dihydroxy-2-amino-7,10-hexadecadiene and 1,3-dihydroxy-2-amino-11,14-eicosadiene. Although examination of the biological activities of these novel ceramides was beyond the scope of these studies, because of the minuscule quantities available from termite secretions, it will be interesting in the future to synthesize these molecules for biological testing. Copyright ©2007 by the American Society for Biochemistry and Molecular Biology, Inc

Formosan subterranean termite (Isoptera: Rhinotermitidae) soldiers regulate juvenile hormone levels and caste differentiation in workers

A caste structure is maintained in termite societies and juvenile hormone (JH) is generally regarded as the most important regulator in these termite colonies. Here, we demonstrate that the soldier caste regulates JH in workers of Coptotermes formosanus Shiraki. Worker termites (80-100 individuals) were placed in petri dishes with 0, 5, 10, or 20% soldiers. JH III titers of groups of these workers were monitored at 14, 28, 42, and 56 d. Any changes in soldier caste proportions also were noted at each sample date. On the first sample date, the JH levels in workers were similar among treatments with different initial soldier proportions, and no new soldiers were formed. Over the next three sample dates, the worker JH levels were higher for low initial soldier proportion treatments and vice versa. Concurrently, soldier formation increased with lower initial soldier proportions. JH titers in workers showed a positive and statistically significant relationship to soldier numbers until a certain soldier proportion was reached. These results provide evidence that soldier caste proportions regulate JH levels and thereby caste differentiation in workers. The means by which this regulatory mechanism may proceed is discussed. © 2005 Entomological Society of America

An efficient and economic asymmetric synthesis of (+)-nootkatone, tetrahydronootkatone, and derivatives

Image Persented A facile route to enantiomerically pure (+)-nootkatone and derivatives has been established through conjunctive stereoselective Grignard/anionic oxy-Cope (AOC) reactions. © 2009 American Chemical Society

Conformational control of selectivity in the dienone-phenol rearrangement

We have explored the dienone-phenol rearrangement of substrates where: only the p-cresol pathway is possible and relative migratory aptitudes should play no role in determining the regiochemistry of the reaction. For these substrates the selectivity of the rearrangement was found to depend on the stereochemistry of the spirocyclic intermediate formed during the course of the rearrangement. Rearrangement of one of these substrates gave-surprisingly-a single regioisomeric product. Selectivity in this case can be correlated with the relative stability of cationic intermediates, which lie on the pathway between spirocycle and final product. © 2007 Elsevier Ltd. All rights reserved

Morphology of Myrmecophila manni, a myrmecophilous cricket (Orthoptera: Gryllidae)

Scanning electron microscopy showed that the myrmecophilous cricket, Myrmecophila manni Schimmer, retains many structural features common to typical gryllids and has few of the morphological features often associated with myrmecophily. However, the mouth parts, particularly the labrum and epipharynx, are highly modified for strigilation and trophallaxis. The structure of the ovipositor is unique in that it can expand greatly to permit the passage of large eggs. This cricket also differs from typical gryllids in having stemmata instead of compound eyes, a feature probably related to its life inside dark ant nests where it does not need good vision. Behavioral, rather than morphological, attributes are probably more important in adapting the crickets for life with ants

Toxicity and behavioral effects of nootkatone, 1,10-dihydronootkatone, and tetrahydronootkatone to the formosan subterranean termite (Isoptera: Rhinotermitidae)

Toxicity and behavioral effects of nootkatone and two of its derivatives, 1,10-dihydronootkatone and tetrahydronootkatone, to Coptotermes formosanus Shiraki were investigated on workers from two different colonies by using topical application assays, repellency assays, and sand barrier assays. The acute toxicity of the nootkatones on workers from both colonies increased as the saturation of the molecule increased, but the difference was significant for only one colony. The results of the repellency assays showed a similar trend of efficiency; the threshold concentration for significant repellency was four-fold higher in nootkatone treatments (50 ppm) than in the reduced derivatives 1,10-dihydronootkatone or tetrahydronootkatone (12.5 ppm). In sand barrier assays, a concentration of 100 ppm of any of the three chemicals significantly reduced termite survival, tunnel building, and food consumption after a 12-d exposure. Termites preexposed tolOO ppm nootkatone-treated sand and placed in containers without nootkatone for 15 d continued to exhibit abnormal feeding and digging behaviors; survivorship, tunneling, and feeding activities were significantly reduced by 83.5, 63.2, and 95.4%, respectively. Termites pretreated for 12 d at concentrations of 50 and 75 ppm nootkatone and tetrahydronootkatone returned to normal digging activity after they were removed from the treatments, but their feeding activity was significantly reduced

Myo-Inositol and phytate are toxic to Formosan subterranean termites (Isoptera: Rhinotermitidae)

© 2014 Entomological Society of America. Several rare and common monosaccharides were screened for toxic effects on the Formosan subterranean termite, Coptotermes formosanus Shiraki, with the aim of identifying environmentally friendly termiticides. myo-Inositol and phytic acid, which are nontoxic to mammals, were identified as potential termite control compounds. Feeding bioassays with termite workers, where both compounds were supplied on filter paper in concentrations from 160.2 to 1,281.7μg/mm3, showed concentration-dependent toxicity within 2 wk. Interestingly myo-inositol was nontoxic when administered to termites in agar (40 mg/ml) in the absence of a cellulosic food source, an unexplained phenomenon. In addition, decreased populations of termite hindgut protozoa were observed upon feeding on myo-inositol but not phytate-spiked filter paper. Radiotracer feeding studies using myoinositol-[ 2-3H] with worker termites showed no metabolism after ingestion over a 2-d feeding period, ruling out metabolites responsible for the selective toxicity